Muraki Y, Hongo S, Sugawara K, Kitame F, Nakamura K
Department of Bacteriology, Yamagata University School of Medicine, Japan.
J Gen Virol. 1996 Apr;77 ( Pt 4):673-9. doi: 10.1099/0022-1317-77-4-673.
The nucleotide sequences of the haemagglutinin-esterase (HE) genes of 18 influenza C virus strains isolated in Japan during the period from 1964 to 1988 (11 published and 7 new sequences) were analysed to examine their evolutionary relationships. The phylogenetic tree constructed by the maximum parsimony method revealed the existence of four discrete lineages (I to IV), one of which (lineage III) may have died out in the late 1970s. Sequential evolution was demonstrated within seven strains of lineage I, which allowed estimation of an evolutionary rate of 0.49 x 10-3 nucleotide substitutions per site per year, a value corresponding to about one-ninth of the rates of human influenza A virus haemagglutinin genes. In the previously proposed immunodominant region on HE protein (positions 178 to 217), there was little or no amino acid sequence divergence among viruses on the same lineage although considerable divergence was seen among those on different lineages, raising the possibility that immune selection may not have played a significant role in the evolution of the glycoprotein, at least not after separation into lineages occurred. It was also found that the HE genes of the seven isolates obtained outside Japan during 1966-1983 could be each assigned to one of lineages I, II and IV, which suggests that influenza C virus is capable of spreading worldwide.
对1964年至1988年期间在日本分离出的18株丙型流感病毒株（11个已发表序列和7个新序列）的血凝素酯酶（HE）基因的核苷酸序列进行了分析，以研究它们的进化关系。用最大简约法构建的系统发育树显示存在四个不同的谱系（I至IV），其中一个谱系（谱系III）可能在20世纪70年代末灭绝。在谱系I的7个毒株中显示出连续进化，由此估计进化速率为每年每个位点0.49×10⁻³个核苷酸替换，该值约相当于人类甲型流感病毒血凝素基因速率的九分之一。在先前提出的HE蛋白免疫显性区域（第178至217位），同一谱系的病毒之间氨基酸序列几乎没有差异，而不同谱系的病毒之间则存在相当大的差异，这增加了免疫选择可能在该糖蛋白的进化中未起重要作用的可能性，至少在谱系分化之后是这样。还发现，1966年至1983年在日本境外获得的7个分离株的HE基因可分别归为谱系I、II和IV中的一个，这表明丙型流感病毒能够在全球传播。
